Solar Capacity For Producing Food Via Vertical Farming
Sustainability has a scale problem. A shift to a more sustainable world will require huge scaling up of energy system capacities
This post continues my thoughts on whether sustainability has a scale problem.
We use the land for our food production quite inefficiently. It follows the 80/20 rule. We use 80 percent of the agricultural land to produce animal products (meat and dairy), which supply 20% of our calories and 37% of our protein needs. On the other hand, crops (grains and produces) use just 20% of the agricultural land but provide 80% of our calories and 63% of our protein needs.
So, what is the problem? The main problem is an environmental disaster from food production. Animal-based products contribute to 60% of agricultural-related emissions while plant-based food contributes to 30%. The ratios for water and other resources are similarly skewed. So, one of the obvious solutions to reduce the environmental impacts of our food production is to use less meat. Other solutions are reducing food waste and stopping energy crops.
Nonetheless, the most popular solution is technological innovations and intensification as it does not require any behavioral, lifestyle, or political changes. A win-win for all, or is it?
I recently read a Medium blog post on vertical farming (VF). The blog was about the electricity consumption of VF and subsequent land requirements of producing that electricity from solar. The numbers seemed unbelievably high so I ran my own numbers and reached (almost) the same conclusion.
I asked a theoretical question. What if we produced all our crops and produce (fruits and vegetables) through vertical farming? How much solar capacity and associated land would be required to meet the total electricity consumption of VF?
Assumptions and calculations
Based on the data (see Figure above), let us assume that the global farming area dedicated to crops and produce is 1 billion hectares. To help you with the conversion, here is the conversion ratio: 1 squared kilometer = 100 hectares. I have excluded land required for animal meat and dairy for now.
VF land requirement (A): 5 million hectares. I assumed that VF needed only 1% of the conventional land area) but achieved twice the yield — meaning 200 times more production — compared to conventional production per hectare of land.
Annual electrical consumption of VF (B): 8760 MWh. I assumed 1 MW power consumption round the clock) per hectare of the planted area, not building footprint. Please refer to this source for further details on electricity consumption. Further, 1 MW of solar produces 1500 MWh of electricity per year (C1) and requires 2 hectares of land (C2).
The total electricity (D) required by VF was 43800 TWh (multiplying A and B parameters), almost twice the global electricity consumption. The solar capacity and land needed to generate this much electricity were (using C1, C2, and D parameters) = 29 TW and 58.4 million hectares of land.
29 TW of solar just to produce entire plant-based food via vertical farming. We currently have only 1 TW of solar. Further, land use efficiency also decreased from the ideal level. We would need 5%, not 0.5%, of the land used in conventional farming.
To be fair, VF has other benefits from water and fertilizer savings. The significant benefits of protecting forests and biodiversity greatly outweigh the costs of additional electricity. Nonetheless, scaling up VF will substantially increase the electricity consumption and need for more renewable energy (and associated land) when we are already struggling to decarbonize the existing electricity mix.